Prussian Blue: Artist' Pigment and Chemists' Sponge.

The article focuses on Prussian blue or ferric ferrocyanide or iron hexacyanoferrate, its history and crystal structure. It states that the study of Prussian blue began with the artists' colormaker, Heinrich Diesbach of Berlin, Germany, who was trying to prepare a crimson lake. Diesbach lacked the necessary potash, so he bought some from a local alchemist, Johan Konrad Dippel. However, Diesbach's obtained a color blue instead of the red he wanted. It turned out the Dippel's potash had been contaminated with his "animal oil," which was a distillate of animal blood, bones and offal. Although the organic component for Prussian blue had been identified, its preparation remained uncover until 1724 when John Woodward published a method that called for dried ox-blood as the starting material.